Sex differences in immune responses and viral shedding following Seoul virus infection in Norway rats

In the field, male rodents are more frequently infected with hantaviruses t han females. This study examined whether patterns of immune responses again st hantavirus differed between the sexes. Male and female Long Evans rats ( Rattus norvegicus) were inoculated with Seoul virus, and antibody and cytok ine responses, as well as virus shedding were assessed. Males were more lik ely to shed virus in saliva, to shed virus through multiple routes (saliva, urine, and feces), and to have viral RNA in the spleen than females. Anti- Seoul virus IgG responses were higher in males than females. In both sexes, splenic IFN gamma and IL-4 production increased following infection. After infection, males had higher Th I immune responses (i.e., IgG2a, IFN gamma, and IL-2) than females: in contrast, Th2 immune responses (i.e., IgG I, IL -4. and IL-10) were similar between the sexes. These data suggest that immu ne responses to Seoul virus differ between the sexes.